Submergible motors are used in a variety of applications where power must be provided in a fluid environment. For example, submergible motors are used in submergible pumping systems utilized in pumping oil and/or other useful fluids from producing wells. In this application, the submergible motor, along with the rest of the submergible pumping system, is inserted into a wellbore and lowered until submerged in the desired oil and/or other fluids. The desired fluids collect in the wellbore and are raised to a point above the earth's surface via the submergible pumping system powered by the submergible motor.
A typical submergible motor, used to pump production fluids from beneath the earth's surface, has an outer housing substantially sealed from the production fluid environment and sized to fit within standard wellbore casings. An exemplary submergible motor is a three-phase induction-type motor having a shaft rotatably mounted within the housing such that it is in general alignment with the axis of the wellbore when residing in the wellbore.
Because of the environments in which such submergible motors are used and the often substantial thrust exerted by these motors, a liquid lubricant, such as mineral oil, is circulated internally. The internal lubricant serves to lubricate the bearings in which the shaft is mounted. It also assists in conducting motor generated heat to the motor housing, and ultimately, to the production fluids in which the motor is submerged.
The lubricating fluid often is contained in a reservoir at the base of the motor, from where it is pumped to the bearings and other components requiring lubrication. In a typical system, the shaft has an axial bore exposed to the fluid in the reservoir as well as cross-drilled bores at each of the bearings and other components requiring lubrication. As the shaft spins, a pumping action is established that moves the liquid lubricant up the axial bore and through the transverse openings to the components requiring lubrication. A filter is disposed either above the reservoir or in the reservoir and interrupts the path of lubricant flow to filter grit or other particles that may cause abrasion and wear if permitted to contact the bearings or other lubricated components.
In existing submergible motors, the filter is not serviceable in the field. Periodically, the submergible motor, along with the rest of the submergible pumping system, must be removed from the well for servicing. The submergible motor is disconnected from the remainder of the submergible pumping system and shipped back to the factory or a servicing location. The motor is then disassembled so that the filter can be cleaned or replaced. Disassembly of conventional motors, sometimes requires the breaking or removal of weldments, making servicing of the filter difficult in a field environment. Of course, the cost and delay associated with shipping motors to a servicing center are undesirable.
It would be advantageous to have a submergible motor that could be disassembled and reassembled in the field, at least to the extent permitting removal and replacement of the internal filter.